1. Field of the Invention
The present invention relates to a magneto-resistance effect element which is configured such that a sense current is flowed in the direction perpendicular to the film surface thereof. The present invention also relates to a magnetic head, a magnetic recording device and a magnetic memory which utilize the magneto-resistance effect element according to the present invention.
2. Description of the Related Art
Recently, the performance of a magnetic device, particularly such as a magnetic head is enhanced by means of Giant Magneto-Resistance Effect (GMR) made of a multilayered magnetic structure. Particularly, since a spin valve film (SV film) can exhibit a larger GMR effect, the SV film has developed the magnetic device such as a magnetic head and MRAM (Magnetic Random Access Memory).
The “spin valve” film has such a structure as sandwiching a non-magnetic spacer layer between two ferromagnetic layers and is configured such that the magnetization of one ferromagnetic layer (often called as a “pinning layer” or “fixed magnetization layer) is fixed by the magnetization of an anti-ferromagnetic layer and the magnetization of the other ferromagnetic layer (often called as a “free layer” or “free magnetization layer”) is rotated in accordance with an external magnetic field. With the spin valve film, the large MR effect can be obtained by the variation of the relative angle in magnetization between the pinned layer and the free layer.
The spacer layer magnetically divides the pinned layer and the free layer so that the magnetization of the free layer can be rotated independently from the magnetization of the pinned layer.
A conventional spin valve film is employed for a CIP (Current In plane)-GMR element, a CPP (Current Perpendicular to Plane)-GMR element and a TMR (Tunneling Magneto Resistance) element. In the CIP-GMR element, a sense current is flowed to the SV film in the direction parallel to the film surface thereof. In the CPP-GMR element and the TMR element, a sense current is flowed to the SV film in the direction almost perpendicular to the film surface thereof.
In such a magneto-resistance effect element as using the SV film to which the sense current is flowed in the direction perpendicular to the film surface, the TMR element uses an insulating layer as the spacer layer and the CPP-GMR element uses a metallic layer as the spacer layer. As the evolution type of the CPP-GMR element, such a magneto-resistance effect element as using a spacer layer with a nano-oxide layer (NOL) containing nano-sized metallic current paths throughout the NOL along the thickness direction thereof is proposed. In this case, a current-confined path (CCP) to exhibit metallic conduction is formed partially in the NOL (Reference 1).
Reference 1 JP-A 2002-208744 (KOKAI)
In any type of conventional magneto-resistance effect element, the pinned layer, the spacer layer and the free layer are fundamentally contained such that an external magnetic field is detected on the relative angle in magnetization between the pinned layer and the free layer.